PHYS 1003 Lecture Notes - Lecture 17: Simple Harmonic Motion, Restoring Force, Equilibrium Point

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scarletmouse10

10 Jan 2017

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Restoring force is proportional to the displacement from equilibrium. : maximum displacement from the equilibrium point (put calculator in radians) Phase angle : radians, defines x at t=0. Usi(cid:374)g newto(cid:374) s seco(cid:374)d law to deter(cid:373)i(cid:374)e force. The frequency of oscillation only depends on the spring constant and the mass (not on displacement) Energy is conserved in simple harmonic motion unless friction exists or. The restoring torque which acting in the direction of an angular displacement. For the torsional pendulum, the expression for angular frequency becomes. Consists of a point mass on the end of a massless string. We assume no air resistance and other non-conservative forces. Only valid for small angles of oscillation. The mass of the bob does not change the frequency or the period. Usually a pendulum cannot be approximated to a point mass. The pendulum is then known as a physical pendulum.

Related Questions

Which of the following statement is not true regarding a mass-spring system that moves with simple harmonic motion in the absence of friction?

a)The total energy of the system remains conserved.

b) The energy of the system is continually transformed between kinetic and potential energy.

c) The total energy of the system is proportional to the square of the amplitude.

d) The potential energy stored in the system is greatest when the mass passes through the equilibrium position.

e) The velocity of the oscillating mass has its maximum value when the mass passes through the equilibrium.

salmonhare521

Good Vibes: Introduction to Oscillations

The conditions that lead to simple harmonic motion are as follows:

There must be a position of stable equilibrium.

There must be a restoring force acting on the oscillating object. The direction of this force must always point toward the equilibrium, and its magnitude must be directly proportional to the magnitude of the object's displacement from its equilibrium position. Mathematically, the restoring force F⃗ is given by ⃗, where is the displacement from equilibrium and k is a constant that depends on the properties of the oscillating system.

The resistive forces in the system must be reasonably small.

Consider a block of mass m attached to a spring with force constant k, as shown in the figure(Figure 1) . The spring can be either stretched or compressed. The block slides on a frictionless horizontal surface, as shown. When the spring is relaxed, the block is located at x=0. If the block is pulled to the right a distance A and then released, A will be the amplitude of the resulting oscillations.

Assume that the mechanical energy of the block-spring system remains unchanged in the subsequent motion of the block.

Part A

After the block is released from x=A, it will

(a) remain at rest

(b) move to the left until it reaches equilibrium and stop there.

(d) move to the left until it reaches x=−A and then begin to move to the right.

The time it takes the block to complete one cycle is called the period. Usually, the period is denoted T and is measured in seconds.

The frequency, denoted f, is the number of cycles that are completed per unit of time: f=1/T. In SI units, f is measured in inverse seconds, or hertz (Hz).

Part B

If the period is doubled, the frequency is

(a) unchanged

(b) doubled

Part C

An oscillating object takes 0.10 s to complete one cycle; that is, its period is 0.10 s. What is its frequency f?

Express your answer in hertz.

Part D

If the frequency is 40 Hz, what is the period T?

Express your answer in seconds.

The following questions refer to the figure (Figure 2) that graphically depicts the oscillations of the block on the spring.

Note that the vertical axis represents the x-coordinate of the oscillating object, and the horizontal axis represents time.

Part E

Which points on the x-axis are located at a distance A from the equilibrium position?

(a) R only

(b) Q only

Part F

Suppose that the period is T. Which of the following points on the t-axis are separated by the time interval T?

(a) K and L

(b) K and M

(d) L and N

(e) M and P

Now assume for the remaining Parts G - J, that the x coordinate of point R is 0.12 m and the t coordinate of point K is 0.0050 s.

Part G

What is the period T?

Express your answer in seconds.

Part H

How much time t does the block take to travel from the point of maximum displacement to the opposite point of maximum displacement?

Express your answer in seconds.

Part I

What distance d does the object cover during one period of oscillation?

Express your answer in meters.

Part J

What distance d does the object cover between the moments labeled K and N on the graph?

Express your answer in meters.

emeraldyak680

PHYS 1003 Lecture Notes - Lecture 17: Simple Harmonic Motion, Restoring Force, Equilibrium Point

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